Train control system



Jan. 3, 1933 w L so 1,893,316

TRAIN CONTROL SYSTEM I Original Filed Nov. 10, 1926 flrlfla d Willldmsan/ mw 6b KW Patented Jan. 3, 1933 UNITED STATES PATENT OFFICE ABB G. ILLIAMSON, F CARNEGIE, PENNSYLVANIA, AssIGNoR TO THE UNION SWITCH & SIGNAL COMPANY, or SWISSVALE, PENNSYLVANIA, A oonroRATIoN or rENNsYLv NIA TRAiN coNTRoL SYSTEM Original application filed November 10,1926, Serial No. 147,403. Divided and. this application filed November 14, 1930.

The present invention relates to train control systems, the train or traffic controlling means being of any suitable character such as signals or retarding or stopping devices or both, and has for its main object and feature the employment of a single source of alternating current for the various circuits of the train-carried equipment and the employment of. an electron discharge device having, in

addition to the thre'eusual elements, a fourth element, here called a: cathode.

This application isa division of application Ser. No. 147,403,1iled November 10, 1926.

In the accompanying drawing the invention is disclosed, by wayof illustration'but not of limitation, in a concrete and preferred form, of which i Fig. 1 is a diagrammatic view of a track circuit that may be employed in connection with the invention; and

Fig. 2 is a diagrammatic view of'a traincarried equipment disclosing one form of the invention.

Carried by thetrain is an electron tube or electron discharge device E, having a plate P, grid G and afilament F. In addition to this, the tube is provided with afourth element ES, here called a cathode, and which is placed closely adjacent to heated filament F, to thereby '1nake'tlie. cathode a source of electronic emission. Apiclreup or receiving circuit is arranged on the train and comprises a pick-up coil-or coils 1;.(arranged in the conventional'way' adjacent to a conductor or to the trafiic rails so as to be in an inductive relation thereto) wire 90, blocking condenser 7, wire 91, grid G, cathode-ES, wires92 and 92 back to coil 1. A condenser C is preferablyconnected across the terminals of tube 1 to tune thecircuit to resonance. at the frequency of the impulses received from the trackway circuit. A plate circuit is" associated with the electron tube, and is here as follows: secondary 133, wire 134, coil of relay 24, wire 135,,plate P, cathode ES, wires 92 and 132 back to secondary 133. It will be noted that the plate circuit'is completed independently of the filament. The filament circuit consists of secondary-"130, filament F and wires 131 and 132. A traflic controlling employed.

Serial No. 495,723.

primary being connected to wires 138 and 139 and supplying both 7 of the secondaries 130 and 133 with energy.

Due to the rectifying action of tube E, current in the plate circuit will flow only when the plate is positive with respect to cathode ES, and said current is therefore a direct current even though an alternating source is Let us assume that the maximum average value ofthe direct current flowing in the plate circuit is 1.00 as long as the filament 1s properly heated and grid'G has the same potential as cathode ES. r i Y Now, when an alternating current is induced in the pic -up coil, this alternating current is applied between grid G and cathode ES, and rectified into a direct current. In other words, current canfiow only whenthe grid is positive with respect to cathode ES. The result of this rectification of the induced ourthe alternating current is polarity that renders grid G negative potential with respect to cathode ES. If condenser 7 were Whatis generally called a leakycondenser, that is, provided with a resistance, it would be charged when the rectified current-is flowing and discharge during the suppression of the swing of the in,- duced current in the other direction, and the result would be to render the grid potential positive and negative, producingthereby a current in the platecircuit having like variations. Condenser 7, however, is nota leaky condensentha't is, it will not discharge, during the suppressed swing of'induced current, the charge built up during the effective swing of induced current. Theresult is, therefore,

that a charge is gradually built up on the A tive potential so long as the induced current flows. When the current ceases to flow in coil 1, the condenser will gradually discharge. The effect of rendering and maintaining the grid negative during the flow of current in the pick-up coil is to choke down the average value of the direct current flowing in the plate circuit. The electron tube therefore acts, in this'case, as a detector to ascertain the flow of current in the track circuit and to establish in response thereto an intermediate value of direct current flowing in the plate circuit. The original value of the direct current in the plate circuit is assumed to be 1.00, and it will now be assumed that 0.40 represents the intermediate value to which the direct current is choked down as the result of a flow of current induced in the'pick-up circuit. HThus the presence or absence of the flow of the train controlling current in the track circuit is reflected on the train by the establishing of a predeterminedvalue of direct currentflowing in the plate circuit.

The utility of the electron tube of the type herewith shown, as a detector ofthe alternating or pulsating current flowing in the trackway element, is to be found in the employment of cathode ES, because the'presence of this cathode renders it unnecessary to conncct the pick-up or receiving circuit with the filament circuit, and thus an alternating current source can be employed as the source for both the filament and plate circuits. ,The tra ic-governing translating device 24 may be of any suitable character such as indicated in application Ser. No. 147,403 previouslyreferred to. 'Briefly, it is'biased in any of the ways known in the art to assume one condition when current of an intermediate average value such'as 0.40 is flowing in its coils, and to assumes-second condition is either increased or decreased with respect to said intermediate value.- As' here shown, relay 24 is a neutral direct-current relay having a neutral armature 28 biased to an intermediate position by spring SS, there being an insulation IN between the spring and the armature. VJhen relay'24 is energized with a'direct current having a maximum value of say 1.00, the upward pull on armature '28 is sufficient to compress spring SS to the extent of breaking the circuit at contact 27, whereas,whei.i current of the intermediate value of 0.40 flows in said relay, armature 28 will be lifted only high enough to close both contacts 2? and 31. Again, when no current or current of a value less than 0.40 is flowing in 24, then the attraction is so weak that armature 28 will drop and open the circuit at contact 31. Therefore, when a current is flowing in the track'way circuit sufficient to properly energize the receiving circuits, armature 28 will hold both contacts: 27 and 31 closed,

whereas, when no effective current is'flowing in. the trackway circuit, armature 28 will disengage contact 27. Likewise, should a wire break in the plate circuit and relay 24 be insufliciently energized or not energized at all, then armature 28 will disengage contact 31. V V

A suitable trackway equipment to cooperate with the train-carried equipment is illustrated in Fig. 1. As there shown, 55 and 56 represent the two'traffic rails arranged into blocks A, B and C by means of insulation 3. The normal direction of tra-flic through said blocks is indicated by the arrow between the rails. At. the ingoing end of each block is a relay, marked 148 in blockG and 148' in block B, connected across the rails by suitable leads, and attheooutgoing end of each block in a track. battery 158 which is connected across the rails by leads 150 and 156. The function of this battery is merely to energize a track relay like ciently powerful to control the train. The

train control current is here supplied from generator 51, in this instance of the alternating current type, by way of hue wires 52 and 53 to a track transformer associated with each block. Taking block B as an example, it will be seen that the primary of track transformer 101 is connected by wires 143 and 144 to line wires 52 and 53. Secondary 145 of the track transformer is connected to rail v 56 by wire 146, armature 147, (of the track relay of the block in advance) contact 149 and Wire 150, and is connected to rail 55 by wire 152, resistance 153 and wires 154 and 156. The function of resistance'153 is to prevent secondary 145 from short circuiting the battery. An impedancecoil 157 is interposed in wire 156 to choke back the flow of alternating current so that it will not pass to the battery. The power supplied from secondary 145 to the rails is of such amplitude as to energize the pick-up circuit on the train. It will now be understood that the presence, in the rails, of current from 145v will choke down the current in the train-carried charged circuit so that it will have the intermediate value of 0.40,and therefore the circuit under control of relay 24 willremain closed.

If block C be unoccupied,then track relay 148 will be energized and train-control current from secondary 145 will pass to the rails of block B, with the result that if a train enters block B from block A, such train will have its cab equipment controlled thereby giving a clear indication. On the other hand, if block C is occupied when a train enters block B from A, then such train, entering block B from A, will receive no train-control current because track relay 148 of block G will have been deenergized by the train in block C thereby dropping armature 147 and opening the circuit from secondary 145 to rails. The efiect of this condition on the train is that a current value of 1.00 is established in the charged circuit passing through relay 24, and that therefore the circuit through 33 is ruptured.

It will further be observed that, although the presence of a train in clock C deenergizes track relay 148 and thus cuts off train-control including: a single source of alternating current, an electron discharge device having a plate, filament and grid, a plate circuit and a" filament circuit associated with said electron discharge devlce, means for supplying cur.-

rent to the filament and plate circuits from.

said source of alternating current, a receiving circuit including the grid of the electron discharge device for controlling'the value of the current flowing in the plate circuit, and means whereby the alternating current flowing in the filament'circuit will notadversely afi'ect the said receiving circuit.

2. A train-carried train control system including: a single source of alternating current, an electron discharge device having a plate, filament, grid and cathode, a plate circuit and a filament circuit associated'with said electron discharge device, means for supplying current to the filament and plate circuits from said source of alternating current, a receiving circuit including the grid and cathode of said device to control the value of the current flowing in the plate circuit, and a traffic-governing means controlled by the current flowing in the plate circuit.

3. A train-carried train control system in- 1 cluding: an electron dischargedevice having trolling circuit, and an electron dischargedevice, having a plate, filament, grid and cathode, controlled by the pick-up circuit and controlling the traffic-controlling circuit.

6. A train-carried train control system including: an electron discharge device; a plate circuit and a filament circuit connected independently of each other to the elements of said electron discharge device; a single source of current to simultaneously supply current to said circuits; a receiving circuit connected to the elements of the electron discharge device to control the value of current flowing in the plate circuit without affecting the current flowing in the filament circuit; and traflic-. governing means under the control of the;

plate circuit.

7. A train carried train cluding: an electron discharge device; a source of alternating current including the primary of a transformer; two secondaries 1 associated with said transformer;a plate circuit and a filament circuit, connected inde-. pendently of each other to the elements of said electron discharge device, one secondary being included in one and another secondary in another of said circuits; a receiving circuit connected to the elements of the electron discharge device to control the value of current flowing in the plate circuit without afiecting the current flowing in the filament circuit; and traific-governing means under the control of the plate circuit.

Signed at Swissvale, in the county of Allegheny,-and State of Pennsylvania this 13th day of November, 1930,

ABBA; e. WILLIAMSON.

a plate, filament, grid and cathode, a receiving circuit including the grid and cathode, a filament circuit, a plate circuit completed independently of the. filament, means to supply current to the plate and filament circuits, and traflic controlling means under the control of the plate circuit.

4:. A train-carried train control system including: an electron discharge device having a plate, filament, grid and cathode, a filament circuit, a plate circuit completed independeptly of the filament, a receiving circuit including the grid and cathode but independent of the filament, means to supply current to the plate and filament circuits, and traflic controlling means under the control of the plate circuit. V

5. A train-carried train controlsystem including: a pick-up circuit inan inductive relation to trackway equipment, a traffic con control system in- 

